An LED is used as a light source of a liquid crystal display apparatus, and thus, in order to adapt to the thinning of the liquid crystal display apparatus, in many case, the LED used as the light source has thickness dimensions of 0.6 mm or 0.8 mm. The LED is a point light source, and in the liquid crystal display apparatus, since the point light source needs to be converted into a planar light beam, a light guide plate formed in a planar shape or a wedge shape by using acryl or polycarbonate as a material is used.
In addition, the display apparatus requires specifications capable of being continuously used for a long time period according to the use thereof. On the other hand, the light source used for the liquid crystal display apparatus has characteristics that the strength of the light source, that is, the brightness as the display apparatus is decreased due to long-time lighting or its use environment. As a method of solving this problem, in product specifications, a light source unit is configured to have a structure of being separable from the display apparatus and when the brightness as the display apparatus is decreased, only the light source unit is replaced.
Although it is not a technique relating to a liquid crystal display apparatus using an LED as a light source, a related art relating to a liquid crystal display apparatus using a cold-cathode tube (CCFL: Cold Cathode Fluorescent Lamp) as a light source will be described with reference to the drawings. FIG. 1 is a sectional view of a light unit according to Related Art 1. FIG. 2 is a plan view illustrating a reflector of a light unit according to Related Art 2, and FIG. 3 is a sectional view of the light unit according to Related Art 2.
As a related art (Japanese Patent Application Laid-Open No. 2008-034287) relating to the light unit having a structure where the light source unit is replaceable, there is a light unit 101 as illustrated in FIG. 1. The light unit 101 includes a light guide plate 102, and a CCFL 103 is provided at the side surface of the light guide plate 102. In addition, in order to allow irradiation light to be efficiently incident on the light guide plate 102, the light unit 101 includes a reflector 105 which is configured with a PET (polyethylene terephthalate) resin plate, a stainless steel plate, or the like.
The reflector 105 is formed so that the light guide plate 102 is pinched by reflection walls 107 and 109. A portion of the light emitting surface 106 of the light guide plate 102 is covered with the reflection wall 109 so that light leakage, which is directly emitting of the irradiation light from the CCFL 103 without passing through the light guide plate 102 toward a liquid crystal display panel 104, is prevented. In addition, in the light unit 101, by sliding the reflection walls 107, 108, and 109 against the light guide plate 102, the worn-out CCFL 103 and reflector 105 can be detached.
In addition, as a related art (Japanese Patent Application Laid-Open No. 2005-158669) relating to the light unit having a structure of preventing light leakage, there is a light unit 201 as illustrated in FIGS. 2 and 3. The light unit 201 includes a light guide plate 202, and a CCFL 203 is provided at the side surface of the light guide plate 202. In addition, in order to allow irradiation light to be efficiently incident on the light guide plate 202, the light unit 201 includes a reflector 205 which is configured with a PET resin plate, a stainless steel plate, or the like.
The reflector 205 is formed so that an edge portion of the light guide plate 202 close to a light source is covered with reflection walls 207, 208, 209, and 210. The reflection wall 208 is bent at a boundary line 212 from the reflection walls 207 and 209 and is configured in a shape along the peripheral surface of the CCFL 203 by a bending groove 213. Particularly, the edge portion of the light emitting surface 206 of the light guide plate 202 is covered with the reflection wall 209, so that light leakage, which is directly emitting of the irradiation light from the CCFL 203 without passing through the light guide plate 202 toward a liquid crystal display panel 204, is prevented. In addition, a light-shielding sheet 211 is provided on the reflection wall 209. In a case where a portion of the reflection wall 209 facing the edge portion of the light guide plate 202 close to the CCFL 203 is intensively irradiated, the light to be reflected by the portion is reduced by the light-shielding sheet 211, so that uniformity of the brightness is improved.